Known in the art is a die casting method called the “PF die casting method”. In this die casting method, the atmosphere in a cavity, runner, and injection sleeve is replaced with an active gas (in general, oxygen) before injecting a melt (metal in a molten state). As a result, due to an oxidation reaction between the oxygen and the melt, the cavity becomes decompressed in state, so a die-cast product which has few pores (blowholes) is obtained (see Patent Literature 1).
Further, as a method of measuring the amount of blowholes of a die-cast product, there is known a method using X-ray CT analysis (see Patent Literature 2).